Newton's First Law

[bandXtrb]

Question on very basic physics:

How can an object be moving and in equilibrium? If it has a force of friction equal to the force using to push it, how can it be moving? Doesn't it require a little more force to get it going from rest?

Thanks.

 

[viewton]

I'm confused...

First law states:

An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

 

[AmazonRasta]

An object doesn't move because of the force you use to push it with. It moves because of the net force is greater with the force you push it with as opposed to the force of friction.

You can push it as hard as you want, but if there's too much friction, it isn't going to go anywhere.

[edit]
Also, you have to realize that there can be other forces acting upon it as well, not just your push. Again, it's the net force that makes the object move.
[/edit]

 

[GoldenGuppy]

If an object is in equilibrium... the force that is acting on it, and the force that the object is applying/exerting are equivalents

Unless you bring friction into consideration - but then again that should still work out to a discrete number. An object can be in equilibrium if there is NO friction, in which case it would be moving on forever and ever, and ever, and ever, and ever.... or so I think... never tried it

)(GG)

 

[GoldenGuppy]

Wow - look at the "SCHOOL" of fish that are responding.. get it?! School?! FISH!? PHYSICS?!

PHYSICS = SCHOOL = Group of fish!!?

ROFLMAOPIMP

.....

(SHUT UP GG, you damn nerd)



)(GG)

 

[bandXtrb]

<< It moves because of the net force is greater with the force you push it with as opposed to the force of friction. >>


Okay, so it does need more force than friction for it to start moving, so it's not at equilibrium.

But once it's in motion, at a uniform speed, it's in equilibrium , it has equal forces canceling each other out, right?

 

[AmazonRasta]

<< But once it's in motion, at a uniform speed, it's in equilibrium , it has equal forces canceling each other out, right? >>



Yup. That's usually what "uniform speed" means. It's moving at a constant speed, no acceleration, no deceleration.

 

[Capn]

"uniform speed" is a trick term, since speed means the magnitude of the velocity. If you put a rock on a string and spin it around your head, it will have constant speed, but not velocity. Plus, the net force on the rock is not zero.

Basically, newtons first law says Fnet=m*a. If the net forces on the object are 0, it will not accelerate.